Anne Sinclair, Dominique Strauss-Kahn's wife, visits husband at Rikers Island prison but IMF chief could be out of jail by the weekend

Dominique Strauss-Kahn and his wife, Anne Sinclair, who visited the IMF chief in prison. The New York grand jury will hear evidence before deciding on a trial. Photograph: Alexander Joe/AFP/Getty Images

The 32-year-old woman allegedly attacked by the head of the International Monetary Fund, Dominique Strauss-Kahn, is expected to testify to the grand jury deciding whether to prosecute him. Strauss-Kahn, 62, is hoping to be granted bail on Thursday as his lawyers return to court to contest charges of sexual assault and attempted rape.

He is being held at the Rikers Island prison in New York. Authorities have confirmed he is under suicide watch, fitted with a medical device to make sure he does not stop breathing during the night, and is checked on 24 hours a day.

His wife, Anne Sinclair, visited him in jail yesterday. "I do not believe for a single second the accusations levelled against my husband," she said in a statement.

Strauss-Kahn is accused of attacking the maid in his suite at the Sofitel hotel in Manhattan around lunchtime on Saturday. Prosecutors are assessing DNA and other evidence from Strauss-Kahn, from the woman, and from the scene of the alleged crime. Investigators have taken a piece of carpet from Strauss-Kahn's hotel suite to test for DNA evidence, law enforcement officials told the Associated Press.

Grand jurors are due to announce their decision on Thursday, and lawyers believe it is almost certain that a case will be brought against Strauss-Kahn.

A growing number of women are coming forward to claim they were the victims of his unwanted sexual advances. Last night Kristin Davis, the self-styled Manhattan madam who supplied prostitutes to former New York governor Eliot Spitzer, claimed Strauss-Kahn had also been a client. She said one $1,200 an hour escort refused to see him again because he had been "aggressive".

On Wednesday the IMF chief's lawyers made a second application for bail, offering $1m in cash and pledging to keep him under house arrest in Manhattan with an electronic ankle bracelet to monitor his movements. The bailing hearing has been set down to be heard on Thursday.

This week, Manhattan's chief assistant district attorney, Daniel Alonso, successfully argued that Strauss-Kahn was a flight risk, and compared him to film director Roman Polanski, who fled the US after he made a plea bargain admitting underage sex but was then faced with jail.

John Coffee, a professor at Columbia Law School, said Strauss-Kahn could be out of jail by the weekend, and he expected that his lawyer, Benjamin Brafman, could come up with an arrangement pending trial that would satisfy the judge.

Coffee said Brafman was one of the most experienced lawyers in the US and would more than likely find a solution that would grant bail.

"Even Bernie Madoff got bail," said Coffee. "And he was a flight risk." Coffee said that, like Madoff, Strauss-Kahn might have to employ an expensive 24-hour surveillance team to monitor his movements while he is placed under effective house arrest in an apartment or hotel.

The woman Strauss-Kahn allegedly attacked is now in hiding. An immigrant from Guinea in west Africa, she has not been named. Her lawyer, Jeffrey Shapiro, said yesterday her life had been turned "upside down" and she had been unable to return to her home because of the press attention; he also said that she strongly contested what has been suggested will be Strauss-Kahn's line of defence, that the sex was consensual.

Pressure is mounting for Strauss-Kahn to resign as IMF managing director. Lawyers for the institution are attempting to contact him to clarify his position; its officials have not spoken to him since arrest. The US treasury secretary, Timothy Geithner, and European finance ministers have all made it clear they believe he should resign, in view of the institution's central role in global finance.

Sources close to the IMF say there is a split among its board: some want him to go, and some say it should not bow to pressure. Strauss-Kahn's deputy, John Lipsky, has stepped in on an interim basis, but both had planned to retire shortly. The race to succeed Strauss-Kahn has now intensified, with candidates from the developing world pushing for senior jobs traditionally dominated by Europeans.

Some IMF members want Strauss-Kahn to resign as soon as possible, arguing that the scandal is damaging the institution; others say he has yet to give his side of the story and maintains his innocence, and the IMF should not bend to pressure. IMF officials did not return calls for comment.